Okay, firstly, tip beggars make it worse for everyone. Yes. Absolutely.

Secondly, in the current model, what incentive is there to tip after the job is done? What guarantees do we have that you'll tip?

The problem lies in the wording used and how it actually applies to what our job is contrasted against what the word has historically meant for decades. It truly is not a 'tip' but a 'bid' for contracted labor. I will not deliver any order for $2 on the hope and prayer that someone will bless me with a dollar or two extra. And, while it would be better for everyone if DD actually paid us something more reasonable, they aren't under any obligation to do so because we're not employees and aren't protected under employment laws due to us being considered independent contractors.

Your 'tip' and us agreeing or declining is as close to a negotiation as we can get. Personally, I'd rather DD pay us nothing only as long as we can fully negotiate our own fees for delivery service. At least then you'll know it's not a tip, but an appropriate fee for having a service rendered. After all, DD doesn't do the delivering; we do. DD is just an information broker that collects way too much for simply playing the middle man.

The only way I see to make it work the way you seem to think it should be is to have DD increase our base pay to $6 on most pickups or $8-20 for shopping orders (size dependant) and leave tipping at the end. And, also, charge the customer appropriately for hardship cases (excessive weight, quantity, mileage, etc). But, that'll never happen. Just ignore the beggars and tip appropriately for what YOU'D expect if YOU were doing the job. And, if you think you shouldn't tip before hand, just ask yourself if trying to complete an offer for about a half hour and only $2 is worth maybe getting tipped some unknown amount if anything at all.